The use of air cycle air conditioning systems as opposed to vapor cycle systems has become increasingly "environmentally correct" due to growing concern about the depletion of the earth's ozone layer due, inter alia, to release of fluorocarbons, which are used in vapor cycle systems.
One type of air cycle air conditioning system is described in U.S. Pat. No. 4,015,438 and employs inlet air at substantially ambient pressure which is cooled in a heat exchanger and introduced into an enclosure for cooling.
There is described and claimed in applicant's U.S. Pat. No. 5,373,707 a particularly efficient air cycle air conditioning system which employs water as a cooling medium. In this system subatmospheric air is employed as the cooling medium in the heat exchanger, thereby raising the water saturation point for a given temperature and thus the cooling capacity, thus attaining coefficient of performance (COP) values which are approximately twice those of systems which do not evaporate water as a cooling medium.
Although the air cycle air conditioning system of applicant's U.S. Pat. No. 5,373,707 is particularly efficient as compared with other prior art systems which do not employ water as a cooling medium, it is still limited in cooling capacity and COP by the amount of water which can be evaporated in a heat exchanger before the air reaches saturation.